As a aircraft mechanic doing oil samples on aircraft engines and apu's for years, it never crossed my mind to do oil analysis on my vehicle engine oil. Never even heard of it. I've been reading for a couple of months but still feel a little overwhelmed by the amount of information. So help me with some oil recommendations as a starting point. I have a '68 Chevy Stepside that I'm putting an LS1/T56 into and I'm looking at Redline for it. (I found this place through Patman and his posts on LS1tech.com--thanks Patman.) I have a '97 Expedition with almost 80k on it. 90% city driving of 30 minutes or less. It does sit idling for about 40 minutes a day waiting in the school parking lot for the kids to get out of school with the a/c on if this matters. It has the 4.6 engine with auto overdrive. And lastly, a '97 Mustang GT with a 4.6 and 5 speed. It does have 3.73 gears and close to 70k miles on it. 70% highway and the rest in town mileage. It seems to use just a little oil. With the mileage of the two Fords would you guys start doing this now? I used Castrol Synthetic (I know now) religiously with Fram filters (ya', I know now about this too) on both vehicles. Even after the Castrol conspiracy I am still leaning toward a synthetic (a true one this time). Thanks in advance for any help. Sorry about the length.